Researchers at the University of South Carolina have pioneered the development of AlInGaN based insulating gate Heterojunction field effect transistors (HFETs), including AlGaN (barrier)/GaN (channel), AlGaN (barrier)/InGaN (channel), and AlInGaN (lattice matched barrier)/GaN (channel) devices. For example, the first report of AlGaN—GaN and AlGaN—GaN—InGaN (back barrier) double heterojunction-field-effect-transistors (DHFETs) was achieved. Additionally, depletion mode and Enhancement mode HFETs have been fabricated using AlGaN—GaN HFETs using the conventional fluorine based gate recessing process.
However, such high-power fluorine etching is the root cause of material damage, increase leakage currents and pre-mature breakdown of the AlInN—GaN HFETs
Thus, a need exists for methods of manufacturing group III nitride HFETs without the need for such high-power fluorine etching.